Aleksandr Artemyev's lawyer, Anton Filin, told RFE/RL today that Moscow's Investigative Department accepted Artemyev's legal documents.
Artemyev, who works for the online news portal gazeta.ru, was among some 150 protesters detained by police on May 31 on Moscow's Triumfalnaya (Triumph) Square.
He says one of his arms was broken in several places when police took him into custody.
The chairman of the State Duma's Committee for Security Issues, Vladimir Vasilyev, sent official queries today to the chief of the Moscow City Interior Department and the city prosecutor, asking them to provide detailed reports on the detention of the demonstrators.
Ombudsman Vladimir Lukin announced on June 3 that he has suspended a memorandum on cooperation with the Interior Ministry because he considers the police action against the demonstrators to have been illegal.
The Moscow demonstration was one of several across the country in support of freedom of assembly.